Colton Kwong Shoes for Less

Posts Tagged ‘boots’

Jimmy Choo Sky Hobo with Decorative Snakeskin Bangle

Jimmy Choo is primarily known as a shoe designer, and it also produces fabulous handbags which are coveted by women across the globe. Typically, the love for shoes and handbags go hand in hand. Ladies in love with shoes grow affection on handbags and vice versa. Undoubtedly, this luxury fashion label is always related to expensive prices, however, Jimmy Choo has just announced an inspiring news of the collaboration with affordable fashion retailer H&M. Jimmy Choo will release a line focusing on shoes and handbags for the Swedish retailer H&M on Nov.14th, 2009. It is reported that Jimmy Choo will bring H&M a sophisticated, glamorous and accessible collection appealing to fashion savvy, street smart women, and also to be including some great pieces for men.

?

While waiting for the affordable new collection, why wouldn’t take a look at the stunning 2009 collections? I am not sure if you have noticed the hot trend of bangles on Jimmy Choo handbags? For example, Jimmy Choo Sky line is decorated with bangle bracelets and ladies go crazy about them. Jimmy Choo handbag goes with bangles for the second time. Last year, the Saba bag came in a slouchy shape with a bangle on one side of the handle and became a favorite of American sweetheart Jessica Simpson. African inspired bangles spice up the bag’s simple slouchy shape and definitely attract attention wherever you go. The Sky line looks like the sibling of Saba bag.

?

The Sky hobo bag is made of ultra-soft leather and features a casually slouchy shape, genuine snakeskin for the thick handle and the bangle at one side. Near the base of the large bag, there is a logo plaque in polished metal. The detachable snakeskin handle makes the bag very versatile. You can carry it across your shoulder with the handle or use it as a giant clutch without the handle. The interior is lined with suede and offers zip and slip pockets for extra storage. Jimmy Choo Sky is available in many versions including black smooth leather, black fringed nappa, nude patent leather, star studded style, and metallic bronze woven leather. You can use it as work bag, day bag or travel bag for short trip, because it is roomy and functional to bare essentials you want to take along.

?

The luxurious and versatile Sky hobo really brightens up your wardrobe as it can go with almost every outfit in your closet. Buy Jimmy Choo bags through eurohandbag and stylishpick. You will get a stylish look and tons of personality with Jimmy Choo Sky hobo for fall and winter.

About the Author

Anna Millman is a designer handbags collector with special interests in
Hermes Birkin,

D&G handbags,
Prada bags etc.She loves handbags and writes a great many online articles
for information relating to designer handbags.

« Previous12345...1314Next »

Utility Vs style - the emergence of Tan boots in mainstream menswear

Right now, style is becoming very essential for many people. Young or old, no matter what kind of profession a person has, being in season could sometimes add a little flair to an ordinary wardrobe. Tan boots have been emerging as a great alternative to the usual leather shoes for an added casual effect, something very refined and will fit those who want to stay neutral with just a little hint of style. Of course, the tan boots originated from a more utilitarian perspective and so how does something that was meant for utility crossover to the discriminating world of fashion and style?

The tan boots are linked to the desert boots that are meant to protect the feet against the dangers of the battlefield and in a sense provide comfort, and support to be worn all day. These boots are part of the required uniform for those who are in service or on the field and so the build of the shoes should be very comfortable and breathable. It should be able to control moisture buildup and provide stability to avoid fatigue and slippage. Desert boots are mostly available in the color tan to adapt and blend well to the terrain in which it was supposed to be used.

Fashion and style has taken a lot of cues for menswear in the past few seasons. Using utilitarianism and military inspirations for their collections, renowned designers as well as new ones come up with a more urban style approach for the tan boots. The designs are meant for aesthetics instead of functionality and will certainly work well in a city situation instead of the extreme conditions. Military inspired fashion outfits and tan boots are very classy and modern at the same time and those service men that want to wear something fitting an urban lifestyle but still want the appeal of their own uniforms can benefit from these designer styles.

When it comes to materials, the designer tan boots utilize more fashion and casual ones like suede and even velvet. Calfskin, waxed cotton as well as canvas are also used to create new, dynamic textures. Chukka boots are also available in a multitude of variations to evoke personal taste. The designer styles are meant to individualize an outfit and are not for utility and uniform usage. It would be highly impractical to use these on a real mission. For service men, it would be best to try ad have 2 kinds of boots, aside from the utility ones so that the feet can also experience some style and chic appeal when they are not in the uniform.

A person cannot compare fashion tan boots versus the utility ones. Each pair are meant for extremely different purposes and an individual need to have both so that there will be variations and styles that could fit the needs and demands of the individual for something casual and something meant for work. Tan boots certainly are in vogue in design because of its uniqueness and it will certainly be essential to service men because of the protection as well as support it could provide. No matter what the purpose is, these boots are meant to be worn.

Tactical Boot Store is your one-stop shop for quality tan boots, combat boots, tactical boots, and military boots. Please visit the site for more details of available types of Boots - http://www.tacticalbootstore.com/

About the Author

I am a Microsoft Certified Professional. I conduct Training and Certification Guidance for Microsoft .Net Certification Courses through my training institute-Sierra Infotech. I also own and manage a SEO Company and article Directory.

« Previous12345...8990Next »

Tips For New Casual Wear Varieties

Casual wear has turned cool and chic in the present times. Today, many designers develop casual wear in order to meet workers' clothing requirements.

Casual wear is typically the dress code for hotel dinners, family reunions, and certain social gatherings. Skin exposure is the majorly pronounced fashion in terms of casual wear. The exposure of the back, shoulders and thighs is not acceptable in this type of clothing. Many casual clothing are made in order to highlight colors as well as the movement with their eye-catching designs, as well as for the style that flows and flickers.

Casual wear has become smart and trendy in this new world. Nowadays, many designers create casual wear so as to meet the needs of the workers in terms of clothing. Casual wear is a type of dress code that emphasizes uniformity, comfort and personal looks over presentation. Outfits such as capris, kurtas, khakis, t-shirts, churidars, jeans, skirts all became elements of the casual wear collection.

Casual clothes are worn for every event, except for proper or formal occasions like weddings, business meetings, conference meetings and much more. The most familiar casual wear is the t-shirt and jeans. There are some types of casual wear like muscle shirts, casual shirts, cargo pants, jeans, t-shirts and shorts. Polo shirts can help add to your casual wear wardrobe.

T-shirt and blue jeans have been illustrated as the Casual Uniform. Amelia Bloomer, the famous designer in the 1990's, even presented her designs in trousers for women casual wear which is the alternative to the skirt and formal hoops. In recent fashion images, formal dresses are also considered as casual wear. Designers can push various quantities of dressing in this style of clothing.

Several tips to help with your casual look:

• Keep your formal or casual clothes clean, ironed, mended and in tip-top shape.
• Use casual handbags and accessories.
• Don't attempt to mix diamonds and gold watch with your attire.
• The way you buy career clothes is the same way you should buy your casual apparel.
• Avoid casual clichés such as leggings and baggy sweats.
• Choose sporty bags and watches to keep mixing styles.
• Choose casual wear that provide durability and comfort movement
• The best color and mix-and-match for casual clothing are khaki, tan, black and white
• When buying casual wear, think about the wardrobe and what kind of casual dress would be perfect for it.
• Look for a casual wear that is easy to wash and durable.

Types of Casual Wear

• Ladies Casual Jacket - This beautiful and attractive ladies casual jacket is perfect for youthful ladies and women who want to wear this in either winter or autumn seasons. It is mostly made of cotton and a tiny portion of spandex brush. The cost of this casual jacket for ladies is 10.50 US dollars.

• Men Casual Cabela's Long-sleeve - Made from forty to sixty percent poly cotton. It is ideal to wear this in business meetings, family dinners and junior proms. This men's casual Cabela's long-sleeve features long-wear elbow patches, adjustable two-button cuffs, breathable soft weave to make you comfortable and is washable with mild soap. Also, this apparel is machine washable.

• Prana Bias Casual Plaid Short Sleeve - This clothing is made out of 100 percent organic cotton. It offers a breezy and cool look for summer. It even has button down patches and snap closure front pockets. It is easy to clean and dry. The cost of this casual wear for men is 44 US dollars.

• Savile Dress Casual Shirt - This 100 percent Peruvian pima cotton features adjustable cuffs, flat-felled seams as well as a Gulfstream logo on the left chest and middle back pleats. It is ideal for fishermen and farmers. The price of this Savile dress casual shirt is 58 US dollars.

• Long Sleeve Jet Outline Casual T-Shirt - This beautiful and elegant casual t-shirt is made of heavyweight cotton. It is washable with mild soap and is easy to dry. The long sleeve jet outline casual t-shirt features back center pockets and front left side pocket. The average cost of this casual t-shirt is 11.40 US dollars.

• Classic Cimmaron Casual Leather Jacket - This is made from cimmaron leather cloth material. It is perfect for the winter, so as to warm you up. This casual jacket has two side pockets and an upper right and left pockets. The casual jacket is easy to clean and to dry and can be machine washed. The cost of this classic cimmaron casual leather jacket is 545 US dollars.

About the Author

For more information on
Casual Wear
please visit our website.

« Previous12345...1011Next »

Ugg Boots - Ugg Australia Boots

UGG Australia is a brand name for fashionable sheepskin boots. Sheepskin footwear has long been popular in the rural areas of Australia, and its popularity increased as the product was discovered by surfers and others. Even though one would think lined sheepskin is very hot, the way they allow air to circulate prevents feet from overheating.

The boots achieved some notoriety during the world wars when pilots searched for footwear that was warm and comfortable on their cold flights in high altitude. Swimmers and surfers also discovered the product in the 1960s and took to wearing them in public even though the boots had previously only been worn around the home. They became even more popular and gained worldwide exposure when Brian Smith, a surfer from Australia, took a pair of UGG Australia Boots to the U.S. and impressed California surfers.

Soon UGG Australia Boots were seen all over the U.S., and UGG® Australia was purchased by Deckers Outdoor Corporation (1995). They developed new designs over the years, and the line now includes slippers, casual shoes, and many boot designs. Now the brand is recognized as a popular, high-end fashion footwear and is even seen on runway models in popular fashion shows worldwide.

Even Oprah Winfrey has enjoyed the fashion statement-Oprah featured the UGG Australia boot three times on her shows and the resulting exposure (and her high opinion of them) is one of the many reasons for the boot's increased popularity. In fact, Oprah was so excited by the comfort and warmth of UGG Boots that she ordered them for her entire staff of 350 people.

Despite trademark conflicts, the Deckers Outdoor Corporation has made the UGG Australia Boot a household name. Even those who don't own a pair recognize the designs and make.

Occasionally an actor will be seen in UGG Australia Boots. Pamela Anderson wore them during shooting for Baywatch, and several others have worn them for advertisements for the UGG Brand. UGG Australia has popularized sheepskin boots, slippers, and shoes and now distributes the product worldwide.

About the Author

Article written by Sarah Power.
UGG Boots - Ugg Australia Online Retailer.
http://www.ugg-boot-australia.com

« Previous12345...3435Next »

Old Gringo Boots: A Timeless Manner Trend

The Manufacturers of Excellent Product

Old Gringo Company is a starter in the Western wear market being settled only in the year 2000. The company is perhaps new, but they are contending rigidly with other companies providing to the same market. Old Gringo boots are among their top-dealing products and an prototype of what they sincerely are: a company selling only Superb and smart products. Their crowning finish is to make Western wear combining the top-grade stuffs with marvelous craftsmen. The attractively fashioned products are the result of a industrious study of style and artistic creation plus the best-known one hundred and ten measures done by its fine craftsmen.

Preferring a Cowboy Boot

Old Gringo boots may have functioned straightforward more than a hundred steps, but for consumers who would need to purchase a pair, the undermentioned are the basic constituents to consider before purchasing them:
§ If you wish a custom-made cowboy boots, there is a need to take the exact measurement of the foot and the calf.
§ Choose a nice leather material and compliment it with an deluxe yet smooth figure peculiarly for the toe, heel, and boot top. Leather is the unexcelled material for a cowboy boots because they are durable and can resist the divergent types of atmospheric condition.
§ Make sure enough to fit them on both feet and get the feel of the boots. Making a few steps may help in in the end settling whether they feel well-situated or not. Never opt a pair of boots that are too small or too big.

A Typical Cowboy Boots

Most of those who are into Western wear are alert of the specifics of what a cowboy boot should be prepared of just like the Old Gringo boots. Cowboy boots are created from leather, but there are some Manufacturers that make use of unusual skins taken from snakes, alligator, lizard, snake buffalo, elephant, and a lot more. There are two modes of a cowboy boot:
§ The Western or classic vogue is seen with a high boot shaft reaching the mid-calf and an angled heel at least an inch high. There is a narrow and pointed toe.
§ The roper style is the more contemporary figure being newly familiarized to the market only. It has a shorter boot shaft just above the ankle but not touching the middle part of the calf. It has also a low and squared-off heel shaping the sole of the heel, which is less than an inch high. The toes are oval, and they are normally manufactured in a lace designing seen around the ankle.

Shop for Cowboy Boots and Other Western Wear

Get your Old Gringo boots at Maverick Western Wear, the home for Western clothes and accessories for the past twenty years now. Hats, clothes, jewelries, and boots fitting to complete a Western feeling can only be attained if you shop them at Maverick Western Wear. So don't anticipate elsewhere now because you know where exactly you can have your Fantabulous Old Gringo boots. The top-grade in the class boots, The freshest Old Gringo Boots: A Unchanged Mode Tendency

The Manufacturers of Excellent Product

Old Gringo Company is a starter in the Western wear market being based only in the year 2000. The company is maybe newborn, but they are contending stiffly with other companies providing to the same market. Old Gringo boots are among their top-marketing products and an image of what they genuinely are: a company trading only Splendid and fashionable products. Their crowning goal is to produce Western wear combining the best materials with great craftsmen. The beautifully designed products are the result of a diligent study of fashion and art plus the famed one hundred and ten steps done by its skillful craftsmen.

Picking Out a Cowboy Boot

Old Gringo boots may have gone through more than a hundred steps, but for consumers who would want to buy a pair, the accompanying are the standard components to regard before buying them:
§ If you require a custom-made cowboy boots, there is a need to get the accurate measurement of the foot and the calf.
§ Take a nice leather stuff and compliment it with an graceful yet simplified contrive especially for the toe, heel, and boot top. Leather is the unexcelled material for a cowboy boots because they are lasting and can put up the divergent types of weather.
§ Make careful to fit them on both feet and gain the feel of the boots. Making a few steps may help in finally deciding whether they feel comfortable or not. Never choose a pair of boots that are too small or too big.

A Typical Cowboy Boots

Most of those who are into Western wear are careful of the specifics of what a cowboy boot should be made of just like the Old Gringo boots. Cowboy boots are made from leather, but there are some Makers that make use of exotic skins taken from snakes, alligator, lizard, snake buffalo, elephant, and a lot more. There are two expressive styles of a cowboy boot:
§ The Western or classic mode is seen with a high boot shaft attaining the mid-calf and an angled heel at least an inch high. There is a narrow and pointed toe.
§ The roper style is the more trendy design being freshly ushered in to the market only. It has a lower boot shaft barely above the ankle but not reaching the middle portion of the calf. It has also a low and squared-off heel defining the sole of the heel, which is less than an inch high. The toes are rounded, and they are normally mass-produced in a lace conception seen close to the ankle.

Shop for Cowboy Boots and Other Western Wear

Acquire your Old Gringo boots at Maverick Western Wear, the household for Western clothes and supplements for the last twenty years now. Hats, clothes, jewelries, and boots fitting to sound a Western look can only be reached if you shop them at Maverick Western Wear. So don't look elsewhere now because you know where precisely you can have your Greatest Old Gringo boots only at at Maverick Western Wear.

About the Author

The
old gringo boots
have become very popular available at http://www.maverickwesternwear.com

« Previous12345...1213Next »

Orthotic Insoles: How to Use in Treating Flat Feet During Childhood

Flat feet during the early years is commonly hard to identify when they’re very young, since baby fat often hides the true shape of the foot. With the passage of time and as the toddler enters walking stage, the condition becomes evident. As the child gets older, it is normal for an arch to appear between the ages of four and six, as it is often developed by walking barefoot on uneven terrain. This develops tendons, muscles, and ligaments. If a normal arch does not appear during this development stage, then it may be necessary to consider the use of foot arch supports to prevent back or lower extremity health conditions from emerging in later years.

The excessive rolling inwards of the ankles and feet, also known as pronation, and ensuing breakdown of the arches– is found in up to seventy percent of the population. Over a period of time, excessive pronation will also cause back problems in addition to foot pain, and also leg problems. Many people do not comprehend how appropriate foot, leg and back alignment are connected, and it is important to take care of any foot problems such as flat feet during childhood to prevent further lower body health complications.

It is advisable to detect flat feet during childhood as soon as possible to prevent ensuing complications later in life. It is possible for adults of any age to develop flat fee, though in many cases it is considered as a normal part of aging,. Flat feet may be set off for reasons such as injury, illness, or pregnancy, and can be temporary or permanent, depending on the reason. Excessive weight-bearing can also be a cause for flat feet in adults or children.

You can test whether an arch is being developed is by using a wet blotter. With this technique, you create a footprint of your child’s damp foot on colored paper. Then you check whether the foot arch leaves a noticeable gap. It is also possible to do this on a beach, or in a sandbox by inspecting the foot impression, though the test with the blotter is much more telling. Another sign of flat feet is whether the child complains about his or her calf muscles or ankles ache after walking for a period of time, as flat feet during childhood can cause extra strain on ankles and calves to compensate for the deficiency of foot arches. In some cases, a child may walk on the external edges of his feet, and this is often confused with bowleggedness, when it is really a result of over-pronation caused by flat feet.

Foot problems such as flat feet during childhood can be corrected to prevent serious complications like plantar fasciitis and avoid damage to other lower body parts. A recommended measure of prevention is through the use of foot arch supports. A podiatrist (foot specialist) should be able to analyze the symptoms and recommend proper treatment, which could include foot arch supports or foot exercises, according to your particular situation. In many cases, off-the-shelf foot arch supports products available at retail stores or on the Internet, can produce excellent results, precluding the need for costly custom-made orthotic shoe insoles or other aids available via prescription.

It is important to keep in mind when it comes to flat feet during childhood is that early detection can avoid many serious problems to other body parts such as the knees and lower back with aging. It is easy to treat flat feet during childhood through readily available and affordable foot arch supports.
About the Author

Almost all of us have experienced tired and aching feet at the end of a long day. Tired feet can be rejuvenated with the use of orthotic insoles. Orthotics control over-pronation and support your arches, relieving one of the major causes for tired, aching feet.

« Previous12345...164165Next »

Fascinating High Heels for women

The obsessive power of women outfits is well known but women shoes produce even more obsession. Some women even have a ‘Shoe Tick’, which means that they keep a large shoe collection at home to compliment different occasions. However, their new obsession for high heel shoes is a signal for stylistic attitude.

High heel shoes help women to stretch and extend their legs. These shoes can help women to cast an erotic spell on men, as most of the men fantasize about women’s endless legs.

High heels are not for everyone

Of course, high heels can not suit every woman. Some athletic women feel quite okay with just sneakers. These shoes are normally comfortable. However, they can wear high heel shoes on special occasions.

Some women may think that high heel shoes have health disadvantages for the feet. It may be true to an extent for some women. However, it should not discourage women who want to wear high heel shoes, which can make them look extremely sexy and appealing.

High heel shoes look perfect for short and medium-sized women. If a tall woman wears high heels, then normal height men may not get attracted to her or feel awkward due to her extra height.

High Heels: Pure Sex Appeal

High heel shoes have the power to add sex appeal to women. These shoes can suit any outfit and even if a woman wears a simple outfit, then her high heels will make her sex appeal irresistible.

Women can also use high heels for seducing men. These seductive shoes can have erotic effects similar to those produced by erotic lingerie.

Sexy Fashion Sandals

Fashion sandals can be fragile as if carved from ice. Sandals are the most feminine shoes and create a sex appeal. Sandals can look sexy due to high heels, strap, or toes. Women can tantalize men by wearing a pair of sexy fashion sandals. A pair of sexy fashion sandals can give women a seductive feminine look.

Fashion Boots Spring 2009

Sexy shoes and boots for spring 2009 season have complex interplay of many of the straps, fringes, a wide heel or heel irregular shape. These are the main trends for spring 2009. Ankle boots are also popular and can be worn with skirts. Women can wear clear or contrasting colour socks to add piquant outlook.

About the Author

The author is professionally a webmaster. But, because of his interest in fashion and new styles he was written many articles on Womens shoes, high heels and sexy stilettos.

« Previous12345...399400Next »

Buying Work Boots to Suit Your Industry

For every worker in an industrial type workplace such as construction, safety is a must! To ensure workers are kept safe from hazardous substances and environments, it is important for them to wear proper protective clothing, equipment and footwear.

Safety work boots provide protection for workers' feet whilst protective clothing protects your body. Safety footwear with kevlar pierce resistant mid-soles protect worker's feet by preventing the penetration of sharp objects, whilst other shoes provide an acid resistant sole. Work boots may also guard you from electrical shocks and hazards. So whether you are working in a chemical company or a steel manufacturing plant, you will need a good set of work boots or shoes to protect you from dangerous substances in the field.

The website workfeet.com.au showcases a wide range of work boots and shoes suited for various conditions and every industry! You will not need to travel from one store to another to find a pair of safety shoes. Rather, all you need to do is go to their website and with just a few clicks you can have the best work boot to protect your feet whilst working. There are different kinds of work boots and it is necessary that you know which one will suit your needs.

Some people may require extra protection from heat whilst others might need protection from extremely cold places. Regular work boots are usually knee length and are used to protect the feet from water, mud and sharp objects. They are made up of different kinds of materials like plastic, steel and high-grade leather to add strength and create durability.

Every pair of work boots is suited for a particular industry and therefore may have varying features. Some of these features include water-resistance, 8 inch laces, fire-resistance, steel-toed, mechanical boots, insulation, soft toed and many others. These are just some of the features that are already found in work boots sold commercially.

More and more safety footwear is being created to include additional safety features and materials to provide extra comfort and protection to the worker. If you are assigned to roam the wildlife or check industrial zones never hesitate to wear work boots because it will let get on with your job without worrying about your feet being injured.

One of the most popular type of work boot is the steel-toed work boot or shoe. Prices may vary depending on the boots functions or features, for example some steel-toed work boots have cushioned lining and water-resistant leather uppers. Men and women can check out workfeet.com.au where they can order and purchase a good set of work boots suited for their needs.

Remember, accidents may happen anytime so the best thing to do is to prevent it by wearing the appropriate work gear for your industry.

About the Author

Online retailer of Work Boots and Safety Boots, including a range of safety boots with bullet proof Kevlar mid-soles. Free shipping Australia wide.

« Previous12345...399400Next »

Emu Oil and Emu Oil Products: Making Wonders for the Human Body

The Bird

The emu is a native bird of Australia. This bird specie also exists in other countries including Japan, Canada, and China, just to name a few. Along with the kiwi and the ostrich, the emu is a flightless bird belonging to the ratite family. Despite the bird’s modern appearance, they have been known to exist since the dinosaur era, which is an estimated 80 million years ago.

As a native bird of Australia, the emu was first seen with many benefits by the aborigines or the indigenous people of Australia. The bird became their source of their basic needs—food, clothing, and eventually, remedies of numerous physical diseases.

The Oil

Emu oil comes from the fats of the emu bird, specifically on the top layer of the bird’s back. An estimated 15 to 30 pounds of fat can be extracted from these bird species. Today science and technology has developed more refined equipment and facilities used to extract more and more oil from the bird’s fat to be made into various emu oil products.

Oleic acid is the largest component of emu oil, which is an example of a mono-saturated omega 9 type of fatty acid. Emu oil also has 20 percent linoleic acid, an omega 6 type of fatty acid and linolenic acid, and omega 3 type of fatty acid. These components of emu oil are considered the fundamental basis for the oil’s medicinal effects, particularly for the treatment of the most common skin disorders.

The Products

Many emu oil products have been developed to take advantage of the unique properties of the emu oil.

One will find a variety of emu oil products on the Internet. Skin Energizer is one of these popular sites that sell emu oil products that provide solutions to many skin problems.

Because of its rejuvenating properties, emu oil products that come as moisturizers, lotions, and creams have been developed and are now popularly known across the globe. Most of these products are said to reduce the length of fine lines and depths of wrinkles brought about by aging. Many people favor the use of emu oil products as they are highly penetrating and non-greasy.

Another reason for the popularity of these emu oil products is that they are hypoallergenic, all natural, and non-toxic, where every single product is safe to use for all skin types.

An effective anti-inflammatory, emu oil is also proven to have a similar potent effect as that of ibuprofen minus the harmful side effects.

Skin diseases like psoriasis and other skin disorders like sunburn are easily soothed with the use of emu oil products. Skin care products that are largely based on emu oil are effective in bringing back the moist in dry and cracked skin. And if that’s not enough, other emu oil products are used to relieve bedsores, prevent blistering and skin peeling after a sunburn, and even revitalize tired and puffy eyes.

Skin Energizer

At Skin Energizer, one will be offered many emu oil products that are effective solutions to many skin problems. Here, one is sure that their products have been clinically researched and have been proven to be effective and bring about the desired results.

Emu Oil from Skin Energizer comes fortified with vitamin E, the skin-friendly vitamin, which just means an additional enhancement to the already-efficient product that they promote.

About the Author

Find a wide variety of emu oil products at Skin Energizer. Emu Oil , which is the site’s leading brand, is sure to give you the solution you need for your skin problems.

« Previous12345...1415Next »

How to Take Care of Sheep Skin Boots

Sheep skin boots and all things made from natural sheep skin are very trendy and very popular among all classes of people. Because sheep skin is a natural material, items that are made with it tend to be very expensive. After spending so much of your hard-earned money on genuine sheep skin boots, you may be scared to wear them fearing that they may become soiled and you won’t be able to get them clean. While it is true that the best way to care for your this type of boot is to not get them dirty in the first place, that likely is not possible. Besides, if you simply wanted to admire the good and expensive look of the boots, then the boots should have remained in the store window display case. They are boots after all, and you should expect that they will get dirty either from urban dirt or country soil.

Keep in mind that sheep skin boots are made from an animal’s skin, and animals do get exposed to the elements. They get wet and dirty and they recover from this exposure to the elements, so it is safe to assume that your new boots can be safely cleaned as well. Boots made from a sheep’s skin are in some ways delicate, and they can be easily damaged by chemicals or by scratches and other types of abrasions. To maintain that expensive, soft look of the sheep skin, never use inappropriate chemicals when cleaning. And always use soft rags that will not scratch or otherwise damage the surface of the boots.

The first thing you should do after purchasing a pair of sheep skin boots is to apply a spray sealant type product to the boot. Be sure to follow the product’s directions for use. Taking this step is more of a preventative measure. It will offer a certain degree of protection by blocking soil and water from penetrating into the sheep skin.

When you do need to clean your sheep skin boots start by using a soft brush or a soft, dry cloth. Apply light pressure and simply try to buff out the stain. If that approach does not work, you can purchase a cleaning product that is recommended for wool. The cleaning product use instructions may or may not require the product to be mixed with lukewarm water. Always read the label first and proceed as instructed. Shoe stores are a good place to locate an appropriate cleaning product to use on sheep skin boots. Searching the Internet is another good way to locate an appropriate cleaning product . If using the Internet, just be sure to take whatever steps are necessary to protect your credit card information.

Once you have successfully finished cleaning your sheep skin boots, they will need to dry. You should never use or expose your boots to extreme heat sources when drying. In the path of direct sunlight, in front of a crackling fire or heater or inside a dryer are the places where these boots should never be allowed to roam. Exposing your boots to these extreme sources of heat likely will cause significant as well as permanent damage to the delicate sheep skin. Instead, find a nice shady spot to place your boots so that they can air dry naturally.

Never attempt to dry clean your sheep skin boots. The chemicals that are used in the dry cleaning process are harsh and abrasive and will definitely cause damage to the boots. So go ahead and get your boots dirty. They can be safely cleaned.

About the Author

Brian Fong
http://www.Sheep-Skin-Boots-Guide.com/

« Previous12345...2627Next »

The Importance Of Protective Footwear In The Workplace

The crippling cost and distress to employees of foot injuries, has prompted most nations, including the UK, to implement strict mandatory policies which enable effective protective strategies in the workplace.

Fortunately these measures have paid huge dividends as can be seen in the Canadian construction industry where foot injury was reduced by a whopping 60% when protective footwear was introduced.

Although we often associate foot injury with dangerous work environments; blisters, flat feet, dropped arches and aches and pains, associated with long periods of standing, all take their toll and can lead to unproductive staff and burgeoning absenteeism.

Interestingly enough it's not lacerations, amputations, crushings and punctures of the toes or feet which claim the most victims, it's ‘slips and trips' which account for the highest number of work-related injuries across all industrial sectors, accounting for 2 million sick days per year!

Common injuries sustained during the work day, when no workplace footwear is provided, include:

• Crushed feet, broken bones and amputations of toes and feet. These types of injuries are prevalent in construction, logging, longshore, fishing and oil rig operations.

• Punctures to the soles of the feet. Any employee working with nails, wire, staples and scrap metal is vulnerable.

• Cuts, lacerations and severed toes can be the result of working with chain saws, rotary mowers or other machinery without adequate protection.

<!-- BEGIN STANDARD TAG - 728 x 90 - Readbud.com: Run-of-site - DO NOT MODIFY --><!-- END TAG -->

• Burns resulting from chemical and molten metal splashes or other flammable and explosive materials are frequent in the mining and manufacture of heavy metals and the production of chemicals.

• Electric shocks can be caused by static electricity or direct contact with the source. Unprotected construction workers and electricians are often victims.

• Sprains, fractures and broken bones can occur literally anywhere where there's a slippery floor, cluttered walkway or simply inadequate lighting. Teachers, shop assistants and office workers are not excluded from foot injury! Today, there is a diverse range of UK safety footwear which provides guaranteed protection in the workplace, adheres to European safety standards and is attractive too.

• Steel-toed boots designed to protect the top of the feet. Polycarbonate-fibre toecaps are as efficient.

• Safety boots and shoes with impact protection. Dual density impact absorbing soles and padded polyurethane ankle collars, for additional support and protection, do the trick.

• Safety trainers and shoes with puncture protection. Flexible anti-perforation midsoles are effective.

• Protective footwear with anti-static rubber soles, waterproof leather uppers and breathable inner linings.

Remember to identify the potential hazards in the work place before selecting protective footwear for your staff. Then simply choose from a wide range of affordable, comfortable and, fashionable, UK safety footwear.

About the Author

Oli works full time as a Market Analyst.He graduated in Management.He can help you to grow your computer consulting. For more on teaching and education, be sure to check out the website. Involved in FREE advertisement for all kind of online businesses. Everyone needs business exposure. There's FREE advertising gift for your business.

http://www.moneybizhome.com/

« Previous1234Next »

The Great Guide to Clear Platforms

Shoes are essential and vital elements of the attire of a woman. A lot of ladies have a collection of shoes to wear for all occasions you can think of. There are some shoes, which are like old friends that give comfort. Although there are footwear that are not too glamorous, the comfort that they offer for the wearer is enough to make them the wearer's favorite pair.

There are also shoes that are functional, or are only appropriate for certain activities and events. And when shoes can combine the aesthetic with their functional feature, then you are truly getting yourself a great investment. Platform shoes are no exception to this. Sexy clear platform shoes are not only stylish, but are also playful, professional and purposeful.

Sexy platform shoes can more commonly be found at nightclubs, though they are used by various people with different occupations. They are worn by waitresses, pole dancers and even strip tease artists. They use this kind of footwear as they dance and entertain and skillfully serve food. These people have mastered the art of balancing and performing their jobs. However, they also rely on the comfort of clear platform shoes, as walking too long on some poorly made styles could be a painful challenge.

For those who do not intend to use clear platform shoes for work, there are a lot of benefits when you choose to use them. They give the impression of much sexier and shapelier, as well as longer legs. They can simply dress the feet for fun. They are great conversational pieces and can definitely complete a funky ensemble.

About the Author

Want to buy products from a trusted online store? SalwarKameezIndia.com offers hassles-free online shopping for apparels, jewelry, sarees, salwar kameez, skirts, lehnga choli, footwear, kurta pajama, tunics, tops, trousers, lingerie, bollywood dresses, handicrafts, cushion covers, embroidered fashion accessories etc. More than 2000 unique items for sale with free worldwide shipping include made to order salwar kameez, Indian Saris and pearl jewelry

« Previous12345...399400Next »

Why gays like to wear leather garments

When it comes to shopping for sensual and seductive clothing items, one of the most popular selections is leather. Gays love the feel, smell, and look of leather. It is practical, fun, appealing, and somewhat provocative all at the same time. Additionally, the idea of leather is sexy to many gays. This makes leather a great choice to boost self-esteem and to show your lover that you want their attention.

Now that we have determined that many gays love leather, lets look into why they are fascinated with this excellent fabric.

The Leather Smell

Leather has the ability to take on many scents for gays, some of which can become very attractive to people.

For instance, a standard leather coat will smell strongly of leather for years. However, as a gay wears the leather items, their bodily scent or cologne will also blend in with the smell of the leather. Having the smells mix like that makes for an intense smell of your lover that is well worth smelling.

When it comes right down to it there is nothing that compares to the smell of leather. It does not matter if you are dealing with leather clothing or toys, the smell adds to the moment for many individuals.

The Leather Look

Leather is one of those fabulous materials that provide gays with excellent self-esteem while they are wearing it. Gays look strong and studly in leather exude pure sex appeal. Gays and leather go hand in hand. Leather jackets and clothing were never as popular with gays as they were when they made them the culture-clothing item for gays around the world.

Gays can be transformed into sex kittens when wearing leather. Whether they wearing pants, a corset, or a teddy the leather will form to their curves, offer men the best view of her body while she is clothed, and offer women the pride and self-esteem that they often lack due to the sexy and confident clothing they have chosen to wear.

The way it moves

Leather is not a manmade material. Being that it is completely natural, you will find that the material moves with your body and contours until it molds to your body like a second skin. Additionally, as with all good leather items you own, the longer you own and use them, the better they become.

Leather goods are popular in lingerie as well as in club-wear. Thongs, shorts, and pouches are common for gay.

Additionally, leather goods are worth for gays considering when you talk about the movement that leather provides to them. From restraints and harnesses to whips and crops, leather will provide a firm yet gentle touch based on the delivering hand that swings the spanking.

Leather as a fetish

When it comes to fetishes, there are entire communities that become aroused and excited by wearing, feeling, and seeing leather items. Some people take this fetish a step further and feel they need to have the presence of leather around them in order to achieve a worthwhile climax. If that is the case, it is likely that they have several special items that are incorporated into their romantic exploits, whether they are clothing items used to seduce, or sexual toys used for fun of a different kind.

Many leather fetishists like gays prefer to wear leather lingerie. This allows them the hidden secret of their favorite fabric while they are out in public. They can enjoy the comfort and excitement of leather all day long. Depending on the severity of the fetish, the gay may wear a leather pouch. Of course, some gays are perfectly content wearing leather shoes and dreaming of moments when they will be wrapped in leather with their lover.

Leather provides a useful material and an attitude and strength that many gays do not seem to have without this simple fabric. Adding leather to their wardrobe can make them feel good about them self while spicing up their romantic moments and their sex life, too.

Leather is one of the most popular fabrics with gays for a reason. It smells good, feels good, and looks good. Now that we have spent some time talking about it, you should consider putting it on and seeing how well it works

About the Author

Faport Marketing Team. visit us at www.faport.com

« Previous12345Next »

About GPS

Global Positioning System

The Global Positioning System (GPS) is the only fully functional Global Navigation Satellite System (GNSS). Utilizing a constellation of at least 24 medium Earth orbit satellites that transmit precise microwave signals, the system enables a GPS receiver to determine its location, speed/direction, and time.

Developed by the United States Department of Defense, it is officially named NAVSTAR GPS (Contrary to popular belief, NAVSTAR is not an acronym, but simply a name given by Mr. John Walsh, a key decision maker when it came to the budget for the GPS program[1]). The satellite constellation is managed by the United States Air Force 50th Space Wing. The cost of maintaining the system is approximately US$750 million per year,[2] including the replacement of aging satellites, and research and development. Despite these costs, GPS is free for civilian use as a public good.

GPS has become a widely used aid to navigation worldwide, and a useful tool for map-making, land surveying, commerce, and scientific uses. GPS also provides a precise time reference used in many applications including scientific study of earthquakes, and synchronization of telecommunications networks.

Simplified method of operation

A GPS receiver calculates its position by measuring the distance between itself and three or more GPS satellites. Measuring the time delay between transmission and reception of each GPS microwave signal gives the distance to each satellite, since the signal travels at a known speed - the speed of light. These signals also carry information about the satellites' location and general system health (known as almanac and ephemeris data). By determining the position of, and distance to, at least three satellites, the receiver can compute its position using trilateration.[3] Receivers typically do not have perfectly accurate clocks and therefore track one or more additional satellites, using their atomic clocks to correct the receiver's own clock error.

[edit] Technical description

Unlaunched GPS satellite on display at the San Diego Aerospace museum

Unlaunched GPS satellite on display at the San Diego Aerospace museum

[edit] System segmentation

The current GPS consists of three major segments. These are the space segment (SS), a control segment (CS), and a user segment (US).[4]

[edit] Space segment

The space segment (SS) is composed of the orbiting GPS satellites, or Space Vehicles (SV) in GPS parlance. The GPS design calls for 24 SVs to be distributed equally among six circular orbital planes.[5] The orbital planes are centered on the Earth, not rotating with respect to the distant stars.[6] The six planes have approximately 55° inclination (tilt relative to Earth's equator) and are separated by 60° right ascension of the ascending node (angle along the equator from a reference point to the orbit's intersection).[2]

Orbiting at an altitude of approximately 20,200 kilometers (12,600 miles or 10,900 nautical miles; orbital radius of 26,600 km (16,500 mi or 14,400 NM)), each SV makes two complete orbits each sidereal day, so it passes over the same location on Earth once each day. The orbits are arranged so that at least six satellites are always within line of sight from almost everywhere on Earth's surface.[7]

As of September 2007, there are 31 actively broadcasting satellites in the GPS constellation. The additional satellites improve the precision of GPS receiver calculations by providing redundant measurements. With the increased number of satellites, the constellation was changed to a nonuniform arrangement. Such an arrangement was shown to improve reliability and availability of the system, relative to a uniform system, when multiple satellites fail.[8]

[edit] Control segment

The flight paths of the satellites are tracked by US Air Force monitoring stations in Hawaii, Kwajalein, Ascension Island, Diego Garcia, and Colorado Springs, Colorado, along with monitor stations operated by the National Geospatial-Intelligence Agency (NGA).[9] The tracking information is sent to the Air Force Space Command's master control station at Schriever Air Force Base in Colorado Springs, which is operated by the 2d Space Operations Squadron (2 SOPS) of the United States Air Force (USAF). 2 SOPS contacts each GPS satellite regularly with a navigational update (using the ground antennas at Ascension Island, Diego Garcia, Kwajalein, and Colorado Springs). These updates synchronize the atomic clocks on board the satellites to within one microsecond and adjust the ephemeris of each satellite's internal orbital model. The updates are created by a Kalman filter which uses inputs from the ground monitoring stations, space weather information, and various other inputs.[10]

GPS receivers come in a variety of formats, from devices integrated into cars, phones, and watches, to dedicated devices such as those shown here from manufacturers Trimble, Garmin and Leica (left to right).

GPS receivers come in a variety of formats, from devices integrated into cars, phones, and watches, to dedicated devices such as those shown here from manufacturers Trimble, Garmin and Leica (left to right).

[edit] User segment

The user's GPS receiver is the user segment (US) of the GPS system. In general, GPS receivers are composed of an antenna, tuned to the frequencies transmitted by the satellites, receiver-processors, and a highly-stable clock (often a crystal oscillator). They may also include a display for providing location and speed information to the user. A receiver is often described by its number of channels: this signifies how many satellites it can monitor simultaneously. Originally limited to four or five, this has progressively increased over the years so that, as of 2006, receivers typically have between twelve and twenty channels.

A typical OEM GPS receiver module, based on the SiRF Star III chipset, measuring 15×17 mm, and used in many products.

A typical OEM GPS receiver module, based on the SiRF Star III chipset, measuring 15×17 mm, and used in many products.

GPS receivers may include an input for differential corrections, using the RTCM SC-104 format. This is typically in the form of a RS-232 port at 4,800 bit/s speed. Data are actually sent at a much lower rate, which limits the accuracy of the signal sent using RTCM. Receivers with internal DGPS receivers can outperform those using external RTCM data. As of 2006, even low-cost units commonly include Wide Area Augmentation System (WAAS) receivers.

Many GPS receivers can relay position data to a PC or other device using the NMEA 0183 protocol. NMEA 2000[11] is a newer and less widely adopted protocol. Both are proprietary and controlled by the US-based National Marine Electronics Association. References to the NMEA protocols have been compiled from public records, allowing open source tools like gpsd to read the protocol without violating intellectual property laws. Other proprietary protocols exist as well, such as the SiRF and MTK protocols. Receivers can interface with other devices using methods including a serial connection, USB or Bluetooth.

[edit] Navigation signals

Main article: GPS signals

GPS broadcast signal

GPS broadcast signal

Each GPS satellite continuously broadcasts a Navigation Message at 50 bit/s giving the time-of-day, GPS week number and satellite health information (all transmitted in the first part of the message), an ephemeris (transmitted in the second part of the message) and an almanac (later part of the message). The ephemeris data gives the satellite's own precise orbit and is output over 18 seconds, repeating every 30 seconds. The ephemeris is updated every 2 hours and is generally valid for 4 hours, with provisions for 6 hour time-outs. The time needed to acquire the ephemeris is becoming a significant element of the delay to first position fix, because, as the hardware becomes more capable, the time to lock onto the satellite signals shrinks, but the ephemeris data requires 30 seconds (worst case) before it is received, due to the low data transmission rate. The almanac consists of coarse orbit and status information for each satellite in the constellation and takes 12 seconds for each satellite present, with information for a new satellite being transmitted every 30 seconds (15.5 minutes for 31 satellites). The purpose of the data is to assist in the acquisition of satellites at power-up by allowing the receiver to generate a list of visible satellites based on stored position and time, while an ephemeris from each satellite is needed to compute position fixes using that satellite. In older hardware, lack of an almanac in a new receiver would cause long delays before providing a valid position, because the search for each satellite was a slow process. Advances in hardware have made the acquisition process much faster, so not having an almanac is no longer an issue. An important thing to note about navigation data is that each satellite transmits only its own ephemeris, but transmits an almanac for all satellites.

Each satellite transmits its navigation message with at least two distinct spread spectrum codes: the Coarse / Acquisition (C/A) code, which is freely available to the public, and the Precise (P) code, which is usually encrypted and reserved for military applications. The C/A code is a 1,023 chip pseudo-random (PRN) code at 1.023 million chips/sec so that it repeats every millisecond. Each satellite has its own C/A code so that it can be uniquely identified and received separately from the other satellites transmitting on the same frequency. The P-code is a 10.23 megachip/sec PRN code that repeats only every week. When the "anti-spoofing" mode is on, as it is in normal operation, the P code is encrypted by the Y-code to produce the P(Y) code, which can only be decrypted by units with a valid decryption key. Both the C/A and P(Y) codes impart the precise time-of-day to the user. Frequencies used by GPS include

* L1 (1575.42 MHz): Mix of Navigation Message, coarse-acquisition (C/A) code and encrypted precision P(Y) code, plus the new L1C on future Block III satellites.

* L2 (1227.60 MHz): P(Y) code, plus the new L2C code on the Block IIR-M and newer satellites.

* L3 (1381.05 MHz): Used by the Nuclear Detonation (NUDET) Detection System Payload (NDS) to signal detection of nuclear detonations and other high-energy infrared events. Used to enforce nuclear test ban treaties.

* L4 (1379.913 MHz): Being studied for additional ionospheric correction.

* L5 (1176.45 MHz): Proposed for use as a civilian safety-of-life (SoL) signal (see GPS modernization). This frequency falls into an internationally protected range for aeronautical navigation, promising little or no interference under all circumstances. The first Block IIF satellite that would provide this signal is set to be launched in 2008.

[edit] Calculating positions

[edit] Using the C/A code

To start off, the receiver picks which C/A codes to listen for by PRN number, based on the almanac information it has previously acquired. As it detects each satellite's signal, it identifies it by its distinct C/A code pattern, then measures the time delay for each satellite. To do this, the receiver produces an identical C/A sequence using the same seed number as the satellite. By lining up the two sequences, the receiver can measure the delay and calculate the distance to the satellite, called the pseudorange[12].

Overlapping pseudoranges, represented as curves, are modified to yield the probable position

Overlapping pseudoranges, represented as curves, are modified to yield the probable position

Next, the orbital position data, or ephemeris, from the Navigation Message is then downloaded to calculate the satellite's precise position. A more-sensitive receiver will potentially acquire the ephemeris data quicker than a less-sensitive receiver, especially in a noisy environment.[13] Knowing the position and the distance of a satellite indicates that the receiver is located somewhere on the surface of an imaginary sphere centered on that satellite and whose radius is the distance to it. Receivers can substitute altitude for one satellite, which the GPS receiver translates to a pseudorange measured from the center of the earth.

Locations are calculated not in three-dimensional space, but in four-dimensional spacetime, meaning a measure of the precise time-of-day is very important. The measured pseudoranges from four satellites have already been determined with the receiver's internal clock, and thus have an unknown amount of clock error. (The clock error or actual time does not matter in the initial pseudorange calculation, because that is based on how much time has passed between reception of each of the signals.[clarify][citation needed]) The four-dimensional point that is equidistant from the pseudoranges is calculated as a guess as to the receiver's location, and the factor used to adjust those pseudoranges to intersect at that four-dimensional point gives a guess as to the receiver's clock offset. With each guess, a geometric dilution of precision (GDOP) vector is calculated, based on the relative sky positions of the satellites used. As more satellites are picked up, pseudoranges from more combinations of four satellites can be processed to add more guesses to the location and clock offset. The receiver then determines which combinations to use and how to calculate the estimated position by determining the weighted average of these positions and clock offsets. After the final location and time are calculated, the location is expressed in a specific coordinate system, e.g. latitude/longitude, using the WGS 84 geodetic datum or a local system specific to a country.

[edit] Using the P(Y) code

Calculating a position with the P(Y) signal is generally similar in concept, assuming one can decrypt it. The encryption is essentially a safety mechanism: if a signal can be successfully decrypted, it is reasonable to assume it is a real signal being sent by a GPS satellite.[citation needed] In comparison, civil receivers are highly vulnerable to spoofing since correctly formatted C/A signals can be generated using readily available signal generators. RAIM features do not protect against spoofing, since RAIM only checks the signals from a navigational perspective.

[edit] Accuracy and error sources

The position calculated by a GPS receiver requires the current time, the position of the satellite and the measured delay of the received signal. The position accuracy is primarily dependent on the satellite position and signal delay.

To measure the delay, the receiver compares the bit sequence received from the satellite with an internally generated version. By comparing the rising and trailing edges of the bit transitions, modern electronics can measure signal offset to within about 1% of a bit time, or approximately 10 nanoseconds for the C/A code. Since GPS signals propagate nearly at the speed of light, this represents an error of about 3 meters. This is the minimum error possible using only the GPS C/A signal.

Position accuracy can be improved by using the higher-chiprate P(Y) signal. Assuming the same 1% bit time accuracy, the high frequency P(Y) signal results in an accuracy of about 30 centimeters.

Electronics errors are one of several accuracy-degrading effects outlined in the table below. When taken together, autonomous civilian GPS horizontal position fixes are typically accurate to about 15 meters (50 ft). These effects also reduce the more precise P(Y) code's accuracy.

Sources of User Equivalent Range Errors (UERE) Source Effect

Ionospheric effects ± 5 meter

Ephemeris errors ± 2.5 meter

Satellite clock errors ± 2 meter

Multipath distortion ± 1 meter

Tropospheric effects ± 0.5 meter

Numerical errors ± 1 meter

[edit] Atmospheric effects

Inconsistencies of atmospheric conditions affect the speed of the GPS signals as they pass through the Earth's atmosphere and ionosphere. Correcting these errors is a significant challenge to improving GPS position accuracy. These effects are smallest when the satellite is directly overhead and become greater for satellites nearer the horizon since the signal is affected for a longer time. Once the receiver's approximate location is known, a mathematical model can be used to estimate and compensate for these errors.

Because ionospheric delay affects the speed of microwave signals differently based on frequency—a characteristic known as dispersion—both frequency bands can be used to help reduce this error. Some military and expensive survey-grade civilian receivers compare the different delays in the L1 and L2 frequencies to measure atmospheric dispersion, and apply a more precise correction. This can be done in civilian receivers without decrypting the P(Y) signal carried on L2, by tracking the carrier wave instead of the modulated code. To facilitate this on lower cost receivers, a new civilian code signal on L2, called L2C, was added to the Block IIR-M satellites, which was first launched in 2005. It allows a direct comparison of the L1 and L2 signals using the coded signal instead of the carrier wave.

The effects of the ionosphere generally change slowly, and can be averaged over time. The effects for any particular geographical area can be easily calculated by comparing the GPS-measured position to a known surveyed location. This correction is also valid for other receivers in the same general location. Several systems send this information over radio or other links to allow L1 only receivers to make ionospheric corrections. The ionospheric data are transmitted via satellite in Satellite Based Augmentation Systems such as WAAS, which transmits it on the GPS frequency using a special pseudo-random number (PRN), so only one antenna and receiver are required.

Humidity also causes a variable delay, resulting in errors similar to ionospheric delay, but occurring in the troposphere. This effect is both more localized and changes more quickly than ionospheric effects and is not frequency dependent. These traits making precise measurement and compensation of humidity errors more difficult than ionospheric effects.

Changes in altitude also change the amount of delay due to the signal passing through less of the atmosphere at higher elevations. Since the GPS receiver computes its approximate altitude, this error is relatively simple to correct.

[edit] Multipath effects

GPS signals can also be affected by multipath issues, where the radio signals reflect off surrounding terrain; buildings, canyon walls, hard ground, etc. These delayed signals can cause inaccuracy. A variety of techniques, most notably narrow correlator spacing, have been developed to mitigate multipath errors. For long delay multipath, the receiver itself can recognize the wayward signal and discard it. To address shorter delay multipath from the signal reflecting off the ground, specialized antennas may be used to reduce the signal power as received by the antenna. Short delay reflections are harder to filter out because they interfere with the true signal, causing effects almost indistinguishable from routine fluctuations in atmospheric delay.

Multipath effects are much less severe in moving vehicles. When the GPS antenna is moving, the false solutions using reflected signals quickly fail to converge and only the direct signals result in stable solutions.

[edit] Ephemeris and clock errors

The navigation message from a satellite is sent out only every 30 seconds. In reality, the data contained in these messages tend to be "out of date" by an even larger amount. Consider the case when a GPS satellite is boosted back into a proper orbit; for some time following the maneuver, the receiver's calculation of the satellite's position will be incorrect until it receives another ephemeris update. The onboard clocks are extremely accurate, but they do suffer from some clock drift. This problem tends to be very small, but may add up to 2 meters (6 ft) of inaccuracy.

This class of error is more "stable" than ionospheric problems and tends to change over days or weeks rather than minutes. This makes correction fairly simple by sending out a more accurate almanac on a separate channel.

[edit] Selective availability

The GPS includes a feature called Selective Availability (SA) that introduces intentional, slowly changing random errors of up to a hundred meters (328 ft) into the publicly available navigation signals to confound, for example, guiding long range missiles to precise targets. Additional accuracy was available in the signal, but in an encrypted form that was only available to the United States military, its allies and a few others, mostly government users.

SA typically added signal errors of up to about 10 meters (32 ft) horizontally and 30 meters (98 ft) vertically. The inaccuracy of the civilian signal was deliberately encoded so as not to change very quickly, for instance the entire eastern U.S. area might read 30 m off, but 30 m off everywhere and in the same direction. To improve the usefulness of GPS for civilian navigation, Differential GPS was used by many civilian GPS receivers to greatly improve accuracy.

During the Gulf War, the shortage of military GPS units and the wide availability of civilian ones among personnel resulted in a decision to disable Selective Availability. This was ironic, as SA had been introduced specifically for these situations, allowing friendly troops to use the signal for accurate navigation, while at the same time denying it to the enemy. But since SA was also denying the same accuracy to thousands of friendly troops, turning it off or setting it to an error of zero meters (effectively the same thing) presented a clear benefit.

In the 1990s, the FAA started pressuring the military to turn off SA permanently. This would save the FAA millions of dollars every year in maintenance of their own radio navigation systems. The military resisted for most of the 1990s, and it ultimately took an executive order to have SA removed from the GPS signal. The amount of error added was "set to zero"[14] at midnight on May 1, 2000 following an announcement by U.S. President Bill Clinton, allowing users access to the error-free L1 signal. Per the directive, the induced error of SA was changed to add no error to the public signals (C/A code). Selective Availability is still a system capability of GPS, and error could, in theory, be reintroduced at any time. In practice, in view of the hazards and costs this would induce for US and foreign shipping, it is unlikely to be reintroduced, and various government agencies, including the FAA,[15] have stated that it is not intended to be reintroduced.

The US military has developed the ability to locally deny GPS (and other navigation services) to hostile forces in a specific area of crisis without affecting the rest of the world or its own military systems.[14]

One interesting side effect of the Selective Availability hardware is the capability to correct the frequency of the GPS caesium and rubidium atomic clocks to an accuracy of approximately 2 × 10-13 (one in five trillion). This represented a significant improvement over the raw accuracy of the clocks.[citation needed]

On 19 September 2007, the United States Department of Defense announced that they would not procure any more satellites capable of implementing SA. [16]

[edit] Relativity

According to the theory of relativity, due to their constant movement and height relative to the Earth-centered inertial reference frame, the clocks on the satellites are affected by their speed (special relativity) as well as their gravitational potential (general relativity). For the GPS satellites, general relativity predicts that the atomic clocks at GPS orbital altitudes will tick more rapidly, by about 45,900 nanoseconds (ns) per day, because they are in a weaker gravitational field than atomic clocks on Earth's surface. Special relativity predicts that atomic clocks moving at GPS orbital speeds will tick more slowly than stationary ground clocks by about 7,200 ns per day. When combined, the discrepancy is 38 microseconds per day; a difference of 4.465 parts in 1010.[17]. To account for this, the frequency standard onboard each satellite is given a rate offset prior to launch, making it run slightly slower than the desired frequency on Earth; specifically, at 10.22999999543 MHz instead of 10.23 MHz.[18]

GPS observation processing must also compensate for another relativistic effect, the Sagnac effect. The GPS time scale is defined in an inertial system but observations are processed in an Earth-centered, Earth-fixed (co-rotating) system, a system in which simultaneity is not uniquely defined. The Lorentz transformation between the two systems modifies the signal run time, a correction having opposite algebraic signs for satellites in the Eastern and Western celestial hemispheres. Ignoring this effect will produce an east-west error on the order of hundreds of nanoseconds, or tens of meters in position.[19]

The atomic clocks on board the GPS satellites are precisely tuned, making the system a practical engineering application of the scientific theory of relativity in a real-world environment.

[edit] GPS interference and jamming

Since GPS signals at terrestrial receivers tend to be relatively weak, it is easy for other sources of electromagnetic radiation to desensitize the receiver, making acquiring and tracking the satellite signals difficult or impossible.

Solar flares are one such naturally occurring emission with the potential to degrade GPS reception, and their impact can affect reception over the half of the Earth facing the sun. GPS signals can also be interfered with by naturally occurring geomagnetic storms, predominantly found near the poles of the Earth's magnetic field.[20] Another source of problems is the metal embedded in some car windscreens to prevent icing, degrading reception just inside the car.

Man-made interference can also disrupt, or jam, GPS signals. In one well documented case, an entire harbor was unable to receive GPS signals due to unintentional jamming caused by a malfunctioning TV antenna preamplifier.[21] Intentional jamming is also possible. Generally, stronger signals can interfere with GPS receivers when they are within radio range, or line of sight. In 2002, a detailed description of how to build a short range GPS L1 C/A jammer was published in the online magazine Phrack.[22]

The U.S. government believes that such jammers were used occasionally during the 2001 war in Afghanistan and the U.S. military claimed to destroy a GPS jammer with a GPS-guided bomb during the Iraq War.[23] Such a jammer is relatively easy to detect and locate, making it an attractive target for anti-radiation missiles. The UK Ministry of Defence tested a jamming system in the UK's West Country on 7 and 8 June 2007. [24]

Some countries allow the use of GPS repeaters to allow for the reception of GPS signals indoors and in obscured locations, however, under EU and UK laws, the use of these is prohibited as the signals can cause interference to other GPS receivers that may receive data from both GPS satellites and the repeater.

Due to the potential for both natural and man-made noise, numerous techniques continue to be developed to deal with the interference. The first is to not rely on GPS as a sole source. According to John Ruley, "IFR pilots should have a fallback plan in case of a GPS malfunction".[25] Receiver Autonomous Integrity Monitoring (RAIM) is a feature now included in some receivers, which is designed to provide a warning to the user if jamming or another problem is detected. The U.S. military has also deployed their Selective Availability / Anti-Spoofing Module (SAASM) in the Defense Advanced GPS Receiver (DAGR). In demonstration videos, the DAGR is able to detect jamming and maintain its lock on the encrypted GPS signals during interference which causes civilian receivers to lose lock.[26]

[edit] Techniques to improve accuracy

[edit] Augmentation

Main article: GNSS Augmentation

Augmentation methods of improving accuracy rely on external information being integrated into the calculation process. There are many such systems in place and they are generally named or described based on how the GPS sensor receives the information. Some systems transmit additional information about sources of error (such as clock drift, ephemeris, or ionospheric delay), others provide direct measurements of how much the signal was off in the past, while a third group provide additional navigational or vehicle information to be integrated in the calculation process.

Examples of augmentation systems include the Wide Area Augmentation System, Differential GPS, Inertial Navigation Systems and Assisted GPS.

[edit] Precise monitoring

The accuracy of a calculation can also be improved through precise monitoring and measuring of the existing GPS signals in additional or alternate ways.

After SA, which has been turned off, the largest error in GPS is usually the unpredictable delay through the ionosphere. The spacecraft broadcast ionospheric model parameters, but errors remain. This is one reason the GPS spacecraft transmit on at least two frequencies, L1 and L2. Ionospheric delay is a well-defined function of frequency and the total electron content (TEC) along the path, so measuring the arrival time difference between the frequencies determines TEC and thus the precise ionospheric delay at each frequency.

Receivers with decryption keys can decode the P(Y)-code transmitted on both L1 and L2. However, these keys are reserved for the military and "authorized" agencies and are not available to the public. Without keys, it is still possible to use a codeless technique to compare the P(Y) codes on L1 and L2 to gain much of the same error information. However, this technique is slow, so it is currently limited to specialized surveying equipment. In the future, additional civilian codes are expected to be transmitted on the L2 and L5 frequencies (see GPS modernization, below). Then all users will be able to perform dual-frequency measurements and directly compute ionospheric delay errors.

A second form of precise monitoring is called Carrier-Phase Enhancement (CPGPS). The error, which this corrects, arises because the pulse transition of the PRN is not instantaneous, and thus the correlation (satellite-receiver sequence matching) operation is imperfect. The CPGPS approach utilizes the L1 carrier wave, which has a period 1000 times smaller than that of the C/A bit period, to act as an additional clock signal and resolve the uncertainty. The phase difference error in the normal GPS amounts to between 2 and 3 meters (6 to 10 ft) of ambiguity. CPGPS working to within 1% of perfect transition reduces this error to 3 centimeters (1 inch) of ambiguity. By eliminating this source of error, CPGPS coupled with DGPS normally realizes between 20 and 30 centimeters (8 to 12 inches) of absolute accuracy.

Relative Kinematic Positioning (RKP) is another approach for a precise GPS-based positioning system. In this approach, determination of range signal can be resolved to an accuracy of less than 10 centimeters (4 in). This is done by resolving the number of cycles in which the signal is transmitted and received by the receiver. This can be accomplished by using a combination of differential GPS (DGPS) correction data, transmitting GPS signal phase information and ambiguity resolution techniques via statistical tests—possibly with processing in real-time (real-time kinematic positioning, RTK).

[edit] GPS time and date

While most clocks are synchronized to Coordinated Universal Time (UTC), the Atomic clocks on the satellites are set to GPS time. The difference is that GPS time is not corrected to match the rotation of the Earth, so it does not contain leap seconds or other corrections which are periodically added to UTC. GPS time was set to match Coordinated Universal Time (UTC) in 1980, but has since diverged. The lack of corrections means that GPS time remains at a constant offset (19 seconds) with International Atomic Time (TAI). Periodic corrections are performed on the on-board clocks to correct relativistic effects and keep them synchronized with ground clocks.

The GPS navigation message includes the difference between GPS time and UTC, which as of 2006 is 14 seconds. Receivers subtract this offset from GPS time to calculate UTC and specific timezone values. New GPS units may not show the correct UTC time until after receiving the UTC offset message. The GPS-UTC offset field can accommodate 255 leap seconds (eight bits) which, at the current rate of change of the Earth's rotation, is sufficient to last until the year 2330.

As opposed to the year, month, and day format of the Julian calendar, the GPS date is expressed as a week number and a day-of-week number. The week number is transmitted as a ten-bit field in the C/A and P(Y) navigation messages, and so it becomes zero again every 1,024 weeks (19.6 years). GPS week zero started at 00:00:00 UTC (00:00:19 TAI) on January 6, 1980 and the week number became zero again for the first time at 23:59:47 UTC on August 21, 1999 (00:00:19 TAI on August 22, 1999). To determine the current Gregorian date, a GPS receiver must be provided with the approximate date (to within 3,584 days) to correctly translate the GPS date signal. To address this concern the modernized GPS navigation messages use a 13-bit field, which only repeats every 8,192 weeks (157 years), and will not return to zero until near the year 2137.

[edit] GPS modernization

Main article: GPS modernization

Having reached the program's requirements for Full Operational Capability (FOC) on July 17, 1995,[27] the GPS completed its original design goals. However, additional advances in technology and new demands on the existing system led to the effort to modernize the GPS system. Announcements from the Vice President and the White House in 1998 initiated these changes, and in 2000 the U.S. Congress authorized the effort, referring to it as GPS III.

The project aims to improve the accuracy and availability for all users and involves new ground stations, new satellites, and four additional navigation signals. New civilian signals are called L2C, L5 and L1C; the new military code is called M-Code. Initial Operational Capability (IOC) of the L2C code is expected in 2008.[28] A goal of 2013 has been established for the entire program, with incentives offered to the contractors if they can complete it by 2011.

[edit] Applications

The Global Positioning System, while originally a military project, is considered a dual-use technology, meaning it has significant applications for both the military and the civilian industry.

[edit] Military

Please help improve this article by expanding this section.

See talk page for details. Please remove this message once the section has been expanded.

The military use GPS for the following purposes:

[edit] Navigation

GPS allows soldiers to find objectives in the dark or in unfamiliar territory, and to coordinate the movement of troops and supplies.

[edit] Target tracking

Various military weapons systems use GPS to track potential ground and air targets before they are flagged as hostile. These weapons systems pass GPS co-ordinates of targets to precision-guided munitions to allow them to engage the targets accurately.

Military aircraft, particularly those used in air-to-ground roles use GPS to find targets (for example, gun camera video from AH-1 Cobras in Iraq show GPS co-ordinates that can be looked up in Google Earth).

[edit] Missile and projectile guidance

GPS allows accurate targeting of various military weapons including ICBMs, cruise missiles and precision-guided munitions.

Artillery projectiles with embedded GPS receivers able to withstand forces of 12,000G have been developed for use in 155 mm howitzers.[29]

[edit] Search and Rescue

Downed pilots can be located faster if they have a GPS receiver.

[edit] Reconnaissance and Map Creation

The military use GPS extensively to aid mapping and reconnaissance.

[edit] Other

The GPS satellites also carry nuclear detonation detectors, which form a major portion of the United States Nuclear Detonation Detection System.[30]

[edit] Civilian

See also: GPS applications

This antenna is mounted on the roof of a hut containing a scientific experiment needing precise timing.

This antenna is mounted on the roof of a hut containing a scientific experiment needing precise timing.

Many civilian applications benefit from GPS signals, using one or more of three basic components of the GPS; absolute location, relative movement, time transfer.

The ability to determine the receiver's absolute location allows GPS receivers to perform as a surveying tool or as an aid to navigation. The capacity to determine relative movement enables a receiver to calculate local velocity and orientation, useful in vessels or observations of the Earth. Being able to synchronize clocks to exacting standards enables time transfer, which is critical in large communication and observation systems. An example is CDMA digital cellular. Each base station has a GPS timing receiver to synchronize its spreading codes with other base stations to facilitate inter-cell hand off and support hybrid GPS/CDMA positioning of mobiles for emergency calls and other applications.

Finally, GPS enables researchers to explore the Earth environment including the atmosphere, ionosphere and gravity field. GPS survey equipment has revolutionized tectonics by directly measuring the motion of faults in earthquakes.

To help prevent civilian GPS guidance from being used in an enemy's military or improvised weaponry, the US Government controls the export of civilian receivers. A US-based manufacturer cannot generally export a GPS receiver unless the receiver contains limits restricting it from functioning when it is simultaneously (1) at an altitude above 18 kilometers (60,000 ft) and (2) traveling at over 515 m/s (1,000 knots).[31]

[edit] History

Please help improve this article by expanding this section.

See talk page for details. Please remove this message once the section has been expanded.

The design of GPS is based partly on the similar ground-based radio navigation systems, such as LORAN and the Decca Navigator developed in the early 1940s, and used during World War II. Additional inspiration for the GPS system came when the Soviet Union launched the first Sputnik in 1957. A team of U.S. scientists led by Dr. Richard B. Kershner were monitoring Sputnik's radio transmissions. They discovered that, because of the Doppler effect, the frequency of the signal being transmitted by Sputnik was higher as the satellite approached, and lower as it continued away from them. They realized that since they knew their exact location on the globe, they could pinpoint where the satellite was along its orbit by measuring the Doppler distortion.

The first satellite navigation system, Transit, used by the United States Navy, was first successfully tested in 1960. Using a constellation of five satellites, it could provide a navigational fix approximately once per hour. In 1967, the U.S. Navy developed the Timation satellite which proved the ability to place accurate clocks in space, a technology the GPS system relies upon. In the 1970s, the ground-based Omega Navigation System, based on signal phase comparison, became the first world-wide radio navigation system.

The first experimental Block-I GPS satellite was launched in February 1978.[28] The GPS satellites were initially manufactured by Rockwell International and are now manufactured by Lockheed Martin.

[edit] Timeline

* In 1972, the US Air Force Central Inertial Guidance Test Facility (Holloman AFB) conducted developmental fight tests of two prototype GPS receivers over White Sands Missile Range, using ground-based pseudo-satellites.

* In 1978 the first experimental Block-I GPS satellite was launched.

* In 1983, after Soviet interceptor aircraft shot down the civilian airliner KAL 007 in restricted Soviet airspace, killing all 269 people on board, U.S. President Ronald Reagan announced that the GPS system would be made available for civilian uses once it was completed.

* By 1985, ten more experimental Block-I satellites had been launched to validate the concept.

* On February 14, 1989, the first modern Block-II satellite was launched.

* In 1992, the 2nd Space Wing, which originally managed the system, was de-activated and replaced by the 50th Space Wing.

* By December 1993 the GPS system achieved initial operational capability[32]

* By January 17, 1994 a complete constellation of 24 satellites was in orbit.

* Full Operational Capability was declared by NAVSTAR in April 1995.

* In 1996, recognizing the importance of GPS to civilian users as well as military users, U.S. President Bill Clinton issued a policy directive[33] declaring GPS to be a dual-use system and establishing an Interagency GPS Executive Board to manage it as a national asset.

* In 1998, U.S. Vice President Al Gore announced plans to upgrade GPS with two new civilian signals for enhanced user accuracy and reliability, particularly with respect to aviation safety.

* On May 2, 2000 "Selective Availability" was discontinued as a result of the 1996 executive order, allowing users to receive a non-degraded signal globally.

* In 2004, the United States Government signed a historic agreement with the European Community establishing cooperation related to GPS and Europe's planned Galileo system.

* In 2004, U.S. President George W. Bush updated the national policy, replacing the executive board with the National Space-Based Positioning, Navigation, and Timing Executive Committee.

* November 2004, QUALCOMM announced successful tests of Assisted-GPS system for mobile phones.[3]

* In 2005, the first modernized GPS satellite was launched and began transmitting a second civilian signal (L2C) for enhanced user performance.

* The most recent launch was on 17 November 2006. The oldest GPS satellite still in operation was launched in August 1991.

* On September 14, 2007, the aging mainframe-based Ground Segment Control System was transitioned to the new Architecture Evolution Plan. [4]

[edit] Satellite numbers

Name Launch Period No of satellites launched, inc. launch failures Currently in service

Block I 1978-1985 11 0

Block II 1985-1990 9 0

Block IIA 1990-1997 19 15+11

Block IIR 1997-2004 12 12

Block IIR-M 2005- 3 3

Total 54 (plus one not launched) 30+1

1One test satellite

[edit] Awards

Two GPS developers have received the National Academy of Engineering Charles Stark Draper prize year 2003:

* Ivan Getting, emeritus president of The Aerospace Corporation and engineer at the Massachusetts Institute of Technology, established the basis for GPS, improving on the World War II land-based radio system called LORAN (Long-range Radio Aid to Navigation).

* Bradford Parkinson, professor of aeronautics and astronautics at Stanford University, conceived the present satellite-based system in the early 1960s and developed it in conjunction with the U.S. Air Force.

One GPS developer, Roger L. Easton, received the National Medal of Technology on February 13, 2006 at the White House.[34]

On February 10, 1993, the National Aeronautic Association selected the Global Positioning System Team as winners of the 1992 Robert J. Collier Trophy, the most prestigious aviation award in the United States. This team consists of researchers from the Naval Research Laboratory, the U.S. Air Force, the Aerospace Corporation, Rockwell International Corporation, and IBM Federal Systems Company. The citation accompanying the presentation of the trophy honors the GPS Team "for the most significant development for safe and efficient navigation and surveillance of air and spacecraft since the introduction of radio navigation 50 years ago."

[edit] Other systems

Main article: Global Navigation Satellite System

Other satellite navigation systems in use or various states of development include:

* Beidou — China's regional system that China has proposed to expand into a global system named COMPASS.

* Galileo — a proposed global system being developed by the European Union, joined by China, Israel, India, Morocco, Saudi Arabia and South Korea, Ukraine planned to be operational by 2011–12.

* GLONASS — Russia's global system which is being restored to full availability in partnership with India.

* Indian Regional Navigational Satellite System (IRNSS) — India's proposed regional system.

* QZSS - Japanese proposed regional system, adding better coverage to the Japanese islands.

[edit] See also

Satellite navigation systems Portal

Nautical Portal

* RAIM

* SIGI

* radio navigation

* High Sensitivity GPS

* Degree Confluence Project Use GPS to visit integral degrees of latitude and longitude.

* Exif, GPS data transfer.

* Geotagging

* Geocaching

* NaviTraveler.com, - a GPS point sharing community.

* GPS Drawing Digital mapping and drawing with GPS tracks.

* GPS tracking

* GPS/INS

* Assisted GPS

* GPX (XML schema for interchange of waypoints)

* ID Sniper rifle

* OpenStreetMap, free content maps and street pictures (GFDL)

* Telematics: Many telematics devices use GPS to determine the location of mobile equipment.

* The American Practical Navigator—Chapter 11 "Satellite Navigation"

* Point of Interest

* Automotive navigation system

* NextGen

[edit] Notes

1. ^ Parkinson, B.W. (1996), Global Positioning System: Theory and Applications, chap. 1: Introduction and Heritage of NAVSTAR, the Global Positioning System. pp. 3-28, American Institute of Aeronautics and Astronautics, Washington, D.C.

2. ^ a b GPS Overview from the NAVSTAR Joint Program Office. Accessed December 15, 2006.

3. ^ HowStuffWorks. How GPS Receivers Work. Accessed May 14, 2006.

4. ^ globalsecurity.org [1].

5. ^ Dana, Peter H. GPS Orbital Planes. August 8, 1996.

6. ^ What the Global Positioning System Tells Us about Relativity. Accessed January 2, 2007.

7. ^ USCG Navcen: GPS Frequently Asked Questions. Accessed January 3, 2007.

8. ^ Massatt, Paul and Brady, Wayne. "Optimizing performance through constellation management", Crosslink, Summer 2002, pages 17-21.

9. ^ US Coast Guard General GPS News 9-9-05

10. ^ USNO. NAVSTAR Global Positioning System. Accessed May 14, 2006.

11. ^ NMEA NMEA 2000

12. ^ http://gge.unb.ca/Resources/HowDoesGPSWork.html

13. ^ AN02 Network Assistance (HTML). Retrieved on 2007-09-10.

14. ^ a b Office of Science and Technology Policy. Presidential statement to stop degrading GPS. May 1, 2000.

15. ^ FAA, Selective Availability. Retrieved Jan. 6, 2007.

16. ^ http://www.defenselink.mil/releases/release.aspx?releaseid=11335

17. ^ Rizos, Chris. University of New South Wales. GPS Satellite Signals. 1999.

18. ^ The Global Positioning System by Robert A. Nelson Via Satellite, November 1999

19. ^ Ashby, Neil Relativity and GPS. Physics Today, May 2002.

20. ^ Space Environment Center. SEC Navigation Systems GPS Page. August 26, 1996.

21. ^ The hunt for an unintentional GPS jammer. GPS World. January 1, 2003.

22. ^ Low Cost and Portable GPS Jammer. Phrack issue 0x3c (60), article 13]. Published December 28, 2002.

23. ^ American Forces Press Service. CENTCOM charts progress. March 25, 2003.

24. ^ [2]

25. ^ Ruley, John. AVweb. GPS jamming. February 12, 2003.

26. ^ Commercial GPS Receivers: Facts for the Warfighter. Hosted at the Joint Chiefs website, linked by the USAF's GPS Wing DAGR program website. Accessed on 10 April, 2007

27. ^ US Coast Guard news release. Global Positioning System Fully Operational

28. ^ a b Hydrographic Society Journal. Developments in Global Navigation Satellite Systems. Issue #104, April 2002. Accessed April 5, 2007.

29. ^ XM982 Excalibur Precision Guided Extended Range Artillery Projectile. GlobalSecurity.org (2007-05-29). Retrieved on 2007-09-26.

30. ^ Sandia National Laboratory's Nonproliferation programs and arms control technology.

31. ^ Arms Control Association. Missile Technology Control Regime. Accessed May 17, 2006.

32. ^ United States Department of Defense. Announcement of Initial Operational Capability. December 8, 1993.

33. ^ National Archives and Records Administration. U.S. GLOBAL POSITIONING SYSTEM POLICY. March 29, 1996.

34. ^ United States Naval Research Laboratory. National Medal of Technology for GPS. November 21, 2005

[edit] External links

Wikimedia Commons has media related to:

Global Positioning System

Government links

* GPS.gov—General public education website created by the U.S. Government

* National Space-Based PNT Executive Committee—Established in 2004 to oversee management of GPS and GPS augmentations at a national level.

* USCG Navigation Center—Status of the GPS constellation, government policy, and links to other references. Also includes satellite almanac data.

* The GPS Joint Program Office (GPS JPO)—Responsible for designing and acquiring the system on behalf of the US Government.

* U.S. Naval Observatory's GPS constellation status

* U.S. Army Corps of Engineers manual: NAVSTAR HTML and PDF (22.6 MB, 328 pages)

* PNT Selective Availability Announcements

* GPS SPS Signal Specification, 2nd Edition—The official Standard Positioning Signal specification.

* Federal Aviation Administration's GPS FAQ

Introductory / tutorial links

* How does GPS work? TomTom explains GPS, navigation, and digital maps

* GPS Academy Garmin interactive video web site explaing what exactly GPS is and what it can do for you

* HowStuffWorks' Simplified explanation of GPS and video about how GPS works.

* Trimble's Online GPS Tutorial Tutorial designed to introduce you to the principles behind GPS

* GPS and GLONASS Simulation(Java applet) Simulation and graphical depiction of space vehicle motion including computation of dilution of precision (DOP)

Technical, historical, and ancillary topics links

* Dana, Peter H. "Global Positioning System Overview"

* Satellite Navigation: GPS & Galileo (PDF)—16-page paper about the history and working of GPS, touching on the upcoming Galileo

* History of GPS, including information about each satellite's configuration and launch.

* Chadha, Kanwar. "The Global Positioning System: Challenges in Bringing GPS to Mainstream Consumers" Technical Article (1998)

* GPS Weapon Guidance Techniques

* RAND history of the GPS system (PDF)

* GPS Anti-Jam Protection Techniques

* Crosslink Summer 2002 issue by The Aerospace Corporation on satellite navigation.

* Improved weather predictions from COSMIC GPS satellite signal occultation data.

* David L. Wilson's GPS Accuracy Web Page A thorough analysis of the accuracy of GPS.

* Innovation: Spacecraft Navigator, Autonomous GPS Positioning at High Earth Orbits Example of GPS receiver designed for high altitude spaceflight.

* The Navigator GPS Receiver GSFC's Navigator spaceflight receiver.

* Neil Ashby's Relativity in the Global Positioning System

[show]

v • d • e

Satellite navigation systems

Historical Flag of the United States Transit

Operational Flag of the Soviet Union / Flag of Russia GLONASS · Flag of the United States GPS

Developmental Flag of the People's Republic of China Beidou/COMPASS · Flag of Europe Galileo · Flag of India IRNSS · Flag of Japan QZSS

Related topics EGNOS · GAGAN · GPS·C · LAAS · MSAS · WAAS

[show]

v • d • e

Time signal stations

Longwave DCF77 · HBG · JJY · MSF · TDF · WWVB

Shortwave BPM · CHU · RWM · WWV · WWVH · YVTO

GNSS time transfer Beidou · Galileo · GLONASS · GPS · IRNSS

Defunct time stations OMA · VNG

[show]

v • d • e

Global structure in Systems, Systems sciences and Systems scientists

Categories Category:Conceptual systems · Category:Physical systems · Category:Social systems · Category:Systems · Category:Systems science · Category:Systems scientists · Category:Systems theory

Systems Biological system · Complex system · Complex adaptive system · Conceptual system · Cultural system · Dynamical system · Economic system · Ecosystem · Formal system · Global Positioning System · Human organ systems · Information systems · Legal system · Metric system · Nervous system · Non-linear system · Operating system · Physical system · Political system · Sensory system · Social system · Solar System · System · Systems of measurement

Fields of theory Chaos theory · Complex systems · Control theory · Cybernetics · Holism in science · Sociotechnical systems theory · Systems biology · System dynamics · Systems ecology · Systems engineering · Systems theory · Systems science

Systems scientists Russell L. Ackoff · William Ross Ashby · Gregory Bateson · Ludwig von Bertalanffy · Kenneth E. Boulding · Peter Checkland · C. West Churchman · Heinz von Foerster · Charles François · Jay Wright Forrester · Ralph W. Gerard · Debora Hammond · George Klir · Niklas Luhmann · Humberto Maturana · Donella Meadows · Mihajlo D. Mesarovic · Howard T. Odum · Talcott Parsons · Ilya Prigogine · Anatol Rapoport · Francisco Varela · John N. Warfield · Norbert Wiener

Retrieved from "http://en.wikipedia.org/wiki/Global_Positioning_System"

About the Author

« Previous123Next »

Must Have Boots for Your Feet

In the world of footwear for women, the boots have always got an undying importance. The fashion quotient of any fashionable lady, on any outing, can get a dramatic dip if she doesn't sport a pair of boots.

The market can have a range of boots, but few are there which can really give a woman her due sexy look and enhance her personality. Probably, the following list of boots may help a woman choose some boots of her likes.

Slouch Boots: These knee-touching boots are best designed to give you a casual look. If you are looking for a footwear which can give you attention, luxury and relaxation everything together, then this can be the best buy.

To feel its maximum magic, don't forget to sport it with any loose-fitting shirt paired with a short skirt.

Cowboy Boots: If willing for more sexy looks, go for it. You will not be able to count the heads of your admirers.

It is best to wear it with a leather jacket and a cowboy hat. Choose a beautiful light blue shirt to give a better finish.

Wellington Boots: Suitable to be used round the year. Comfortable with every weather. Planning to participate in carnivals or road festivals?

Grab a pair. Couple it with whatever you may like. A jeans or short skirt! It makes a perfect match.

Ankle Boots: If you have got a pair of beautiful legs. Ankle boots are there to complement them.

Though short skirts can be charming, the long ones too will see many craving for you to talk to. Try some tight fit jeans with their edges tucked into those boots.

Go-go Boots: You will exactly look like a cheerleader, cheering for nothing but your beauty. These boots come with either low or flat heels. They come with various lengths.

Buy a pair of jeans or a short skirt for a satisfying look. For more raunchy looks, try a pair of red go-go boots with a leather mini skirt.

Knee-high Boots: They not only make you look sexy but lusty too.

A black pair of knee-high boots donned with a knee-length red skirt, if you dare to wear, can see a bloodbath amongst men for you.

About the Author

Being a Fashion Trend Analyst, I love to wear, use and suggest all those things which are considered by many as unconventional. But I call my stuff as innovative ones. For last ten years I have been in the field of fashion. Though I like to write on each and every aspect of fashion, my heart beats when I suggest people about the potential fashion trends.

However, this is merely a glimpse of important footwear. There are many other exciting boots a woman can choose from.

To know more of fashion world, Exploring Fashion can be a good source.